Exploit Title: SilverStripe CMS - 3.6.2 CSV Excel Macro Injection
Vendor Homepage: https://www.silverstripe.org/
Software Link: https://www.silverstripe.org/download
Discovered by: Ishaq Mohammed
Contact: https://twitter.com/security_prince
Website: https://about.me/security-prince
Category: web apps
Platform: PHP

Description:

In the CSV export feature of the SilverStripe CMS, it's possible for the
output to contain macros and scripts, which if imported without
sanitization into software (including Microsoft Excel) may be executed.

Proof of Concept
Steps to Reproduce:

1. Login with normal user's credentials
2. Access the below URL via your browser:
http://localhost/SilverStripe/admin/myprofile
3. Enter the below payload in the "First Name" field and save the profile"
@SUM(1+1)*cmd|' /C calc'!A0
4. Log in with admin's credentials on a different browser
5. Access te security page at the below link:
http://localhost/SilverStripe/admin/security/
6. Click on "Export to CSV" option and open the exported CSV file in any
Spreadsheet application


Solution:
The issue has been fixed in the latest release of SilverStripe which can be
downloaded from here: https://www.silverstripe.org/download

Reference:
https://www.silverstripe.org/download/security-releases/ss-2017-007

-- 
Best Regards,
Ishaq Mohammed
https://about.me/security-prince